/**
**********************************************************************
* @file     main.c
* @brief    对文件的简要说明
* @details  对文件的详细说明
* @author   jcai
* @date     2022-05-04 00:19:00
* @copyright Copyright &copy; 2022 wy1107412334@163.com All rights reserved
* @version  v0.0.1
*
* \n Email:  wy1107412334@163.com
* \n Blog:   None
* \n Github: https://github.com/wy1107412334
* \n Gitee:  https://gitee.com/git.git1107412334.com
*
**********************************************************************
* @note
* None.
**********************************************************************
* @attention
* None.
**********************************************************************
@verbatim
@endverbatim
**********************************************************************
* @par 历史记录
* 1. v0.0.1: jcai, 2022-05-04 00:19:00
*   - 首次编写
*
*<center>Copyright &copy; 2022 wy1107412334@163.com All rights reserved</center>
**********************************************************************
*/

/* 头文件导入区 --------------------------------------------------- */

#include <SDL/SDL_video.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <SDL/SDL.h>
#include <SDL/SDL_image.h>
#include <SDL/SDL_events.h>
#include <SDL/SDL_timer.h>
#include <SDL/SDL_keysym.h>

typedef struct
{
    int startTicks;
    int pausedTicks;
    int paused;
    int started;
} Timer_t;

typedef struct
{
    int x, y;
    int xVel, yVel;
} Dot_t;



// 窗口属性
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int SCREEN_BPP = 32;

// 帧速率
const int FRAMES_PER_SECOND = 20;
// 圆点的大小
const int DOT_WIDTH = 20;
const int DOT_HEIGHT = 20;

// 画布大小
const int LEVEL_WIDTH = 1280;
const int LEVEL_HEIGHT = 9600;

// 将要使用的表面
SDL_Surface *dot = NULL;
SDL_Surface *background = NULL;
SDL_Surface *screen = NULL;

// 事件结构体
SDL_Event event;

// 摄像机
SDL_Rect camera = {0, 0, SCREEN_WIDTH, SCREEN_HEIGHT};



SDL_Surface *load_image(const char *file)
{
    SDL_Surface *loadedImage = NULL;
    SDL_Surface *optimizedImage = NULL;

    // 通过 SDL_imag 模块加载图片
    loadedImage = IMG_Load(file);
    if (!loadedImage)   return NULL;

    optimizedImage = SDL_DisplayFormat(loadedImage);
    SDL_FreeSurface(loadedImage);
    if (optimizedImage)
    {
        // 映射关键色
        uint32_t keycolor = SDL_MapRGB(optimizedImage->format, 0, 0xff, 0xff);
        // 将所有颜色为 RGB(0x00, 0xff, 0xff) 的像素设为透明
        SDL_SetColorKey(optimizedImage, SDL_SRCCOLORKEY, keycolor);
    }

    return optimizedImage;
}

void apply_surface(int x, int y, SDL_Surface *src, SDL_Surface *dst,
                   const SDL_Rect *clip)
{
    SDL_Rect offset;

    offset.x = x;
    offset.y = y;

    SDL_BlitSurface(src, (SDL_Rect *)clip, dst, &offset);
}

int init()
{
    if (SDL_Init(SDL_INIT_EVERYTHING) == -1)
        return -1;

    screen = SDL_SetVideoMode(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP,
                              SDL_SWSURFACE);
    if (!screen)
    {
        SDL_Quit();
        return -2;
    }

    SDL_WM_SetCaption("Move the Dot", NULL);

    // 给窗口背景填充白色
    SDL_FillRect(screen, &screen->clip_rect,
                 SDL_MapRGB(screen->format, 0xff, 0xff, 0xff));

    return 0;
}

int load_files()
{
    // 加载背景图片
    dot = load_image("dot.bmp");
    if (!dot)    return -1;

    background = load_image("bg.png");
    if (!background)
    {
        SDL_FreeSurface(dot);
        return -2;
    }

    return 0;
}

void clean_up()
{
    SDL_FreeSurface(dot);
    SDL_FreeSurface(background);

    SDL_Quit();
}


void timer_init(Timer_t *tm)
{
    tm->startTicks = 0;
    tm->pausedTicks = 0;
    tm->paused = 0;
    tm->started = 0;
}
void timer_start(Timer_t *tm)
{
    tm->started = 1;
    tm->paused = 0;

    tm->startTicks = SDL_GetTicks();
}
void timer_stop(Timer_t *tm)
{
    tm->started = 0;
}
void timer_pause(Timer_t *tm)
{
    if (tm->started && !tm->paused)
    {
        tm->paused = 1;
        tm->pausedTicks = SDL_GetTicks() - tm->startTicks;
    }
}
void timer_unpause(Timer_t *tm)
{
    if (tm->paused)
    {
        tm->paused = 0;

        tm->startTicks = SDL_GetTicks() - tm->pausedTicks;
        tm->pausedTicks = 0;
    }
}
int timer_get_ticks(Timer_t *tm)
{
    if (tm->started)
    {
        if (tm->paused)
            return tm->pausedTicks;
        else
            return SDL_GetTicks() - tm->startTicks;
    }
    return 0;
}
int timer_is_started(Timer_t *tm)
{
    return tm->started;
}
int timer_is_paused(Timer_t *tm)
{
    return tm->paused;
}


void dot_init(Dot_t *dt)
{
    dt->x = 0;
    dt->y = 0;

    dt->xVel = 0;
    dt->yVel = 0;
}
void dot_handle_input(Dot_t *dt)
{
    if (event.type == SDL_KEYDOWN)
    {
        switch (event.key.keysym.sym)
        {
        case SDLK_UP: dt->yVel -= DOT_HEIGHT / 2; break;
        case SDLK_DOWN: dt->yVel += DOT_HEIGHT / 2; break;
        case SDLK_LEFT: dt->xVel -= DOT_WIDTH / 2; break;
        case SDLK_RIGHT: dt->xVel += DOT_WIDTH / 2; break;
        default: break;
        }
    }
    else if (event.type == SDL_KEYUP)
    {
        switch (event.key.keysym.sym)
        {
        case SDLK_UP: dt->yVel += DOT_HEIGHT / 2; break;
        case SDLK_DOWN: dt->yVel -= DOT_HEIGHT / 2; break;
        case SDLK_LEFT: dt->xVel += DOT_WIDTH / 2; break;
        case SDLK_RIGHT: dt->xVel -= DOT_WIDTH / 2; break;
        default: break;
        }
    }
}
void dot_move(Dot_t *dt)
{
    dt->x += dt->xVel;
    if ((dt->x < 0) || ((dt->x + DOT_WIDTH) > LEVEL_WIDTH))
        dt->x -= dt->xVel;

    dt->y += dt->yVel;
    if ((dt->y < 0) || ((dt->y + DOT_HEIGHT) > LEVEL_HEIGHT))
        dt->y -= dt->yVel;
}
void dot_show(const Dot_t *dt)
{
    apply_surface(dt->x - camera.x, dt->y - camera.y, dot, screen, NULL);
}
void dot_set_camera(Dot_t *dt)
{
    camera.x = (dt->x + DOT_WIDTH / 2) - SCREEN_WIDTH / 2;
    camera.y = (dt->y + DOT_HEIGHT / 2) - SCREEN_HEIGHT / 2;

    if (camera.x < 0)
        camera.x = 0;
    if (camera.y < 0)
        camera.y = 0;

    if (camera.x > (LEVEL_WIDTH - camera.w))
        camera.x = LEVEL_WIDTH - camera.w;
    if (camera.y > (LEVEL_HEIGHT - camera.h))
        camera.y = LEVEL_HEIGHT - camera.h;
}



/**
**********************************************************************
* @brief    简要说明
* @details  详细说明
* @param    none
* @param[in]     a: 该参数用于输入
* @param[in,out] b: 该参数用于输入和输出
* @param[out]    c: 该参数用于输出
* @retval  none
* @retval  0 函数成功
* @retval  1 函数失败
* @return  返回0成功；否则失败
* @note    none
*/
int main(int argc, char *argv[])
{
    Timer_t fps;    // 跟踪帧数
    Dot_t dt;
    int quit = 0;

    if (init() != 0)
    {
        fprintf(stderr, "SDL初始化失败\n");
        return EXIT_FAILURE;
    }
    if (load_files() != 0)
    {
        fprintf(stderr, "SDL加载 background.png 失败\n");
        return EXIT_FAILURE;
    }

    dot_init(&dt);

    // 初始化定时器
    timer_init(&fps);

    while (!quit)
    {
        // 开始定时
        timer_start(&fps);

        // 处理SDL的事件
        while (SDL_PollEvent(&event))
        {
            // 处理圆点相关事件
            dot_handle_input(&dt);

            // 如果用户点击了窗口右上角的关闭按钮
            if (event.type == SDL_QUIT)
            {
                quit = 1;
                printf("处理退出事件\n");
                break;
            }
        }

        // 移动圆点的位置
        dot_move(&dt);
        // 设置摄像机
        dot_set_camera(&dt);

        // 显示背景图
        apply_surface(0, 0, background, screen, &camera);

        // 显示圆点的新位置
        dot_show(&dt);

        // 更新窗口
        if (SDL_Flip(screen) == -1)
        {
            fprintf(stderr, "SDL更新窗口失败\n");
            break;
        }

        // 控制帧速率
        if (timer_get_ticks(&fps) < (1000 / FRAMES_PER_SECOND))
            SDL_Delay((1000 / FRAMES_PER_SECOND) - timer_get_ticks(&fps));
    }

    clean_up();

    return 0;
}




/***  Copyright (C) 2022 wy1107412334@163.com All rights reserved ***/
/****************************** END OF FILE *************************/

